Substrate manufacturing and processing methods

Abstract

To provide a method for manufacturing a substrate, which can improve the throughput when manufacturing a substrate from a structure such as an ingot by utilizing a laser beam without increasing the output of the laser beam. [Solution] A method for manufacturing a substrate from a structure made of a single crystal material includes a separation layer formation step in which a laser beam having a wavelength that transmits through the single crystal material is irradiated from the surface side to form a separation layer inside the structure, the separation layer including a modified portion and cracks extending from the modified portion, and a separation step in which the substrate is separated from the structure starting from the separation layer. In the separation layer formation step, the laser beam is branched to form a plurality of focal points aligned along a first direction parallel to a specific crystal plane of the single crystal material, and the structure and the plurality of focal points are moved relatively along a second direction parallel to each of the surface and the specific crystal plane, thereby forming the separation layer.

Description

[Technical Field]

[0001] The present invention relates to a substrate manufacturing method for manufacturing a substrate from a structure made of a single crystal material, and a processing method for forming a peeling layer including a modified portion and a crack extending from the modified portion inside the structure made of a single crystal material. [Background technology]

[0002] Semiconductor device chips are typically manufactured using cylindrical substrates made of single-crystal materials such as silicon, silicon carbide, gallium nitride, lithium tantalate (LT), or lithium niobate (LN), which are cut from cylindrical structures (e.g., ingots) using, for example, a wire saw (see, for example, Patent Document 1).

[0003] However, when cutting a substrate from an ingot using a wire saw, the cutting width is relatively large, at around 300 μm. Furthermore, the surface of the substrate cut in this way has minute irregularities, and the substrate is curved overall (warped). Therefore, when using this substrate to manufacture chips, the surface of the substrate must be flattened by lapping, etching, and / or polishing.

[0004] In this case, the amount of semiconductor material ultimately used as the substrate is about two-thirds of the total ingot volume. In other words, about one-third of the total ingot volume is discarded during the process of cutting the substrate from the ingot and flattening the substrate surface. Therefore, productivity is low when manufacturing substrates using a wire saw in this way.

[0005] In view of this, a method has been proposed in which an ingot is irradiated from the surface side with a laser beam having a wavelength that is transmitted through the single crystal material to form a peeling layer inside the ingot that includes a modified portion and cracks extending from the modified portion, and then the substrate is separated from the ingot using this peeling layer as a starting point (see, for example, Patent Document 2). When substrates are manufactured from ingots using this method, substrate productivity can be improved compared to when substrates are manufactured from ingots using a wire saw. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-94221 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-111143 Summary of the Invention [Problem to be solved by the invention]

[0007] This method is a so-called sheet-based method in which substrates are produced one by one from an ingot. On the other hand, when producing substrates from an ingot using a wire saw, it is possible to produce multiple substrates from an ingot at the same time. Therefore, when producing substrates from an ingot using a laser beam, there is a risk of reduced throughput.

[0008] In order to improve the throughput when manufacturing substrates from ingots using a laser beam, for example, the output of the laser beam irradiated onto the ingot can be increased. This increases the length of cracks extending from the modified portions formed inside the ingot. As a result, the time required to form a peeling layer, which serves as the starting point for separating the substrate from the ingot, can be shortened.

[0009] However, in order to increase the output of the laser beam, it is necessary to increase the size of the laser oscillator that generates the laser beam. Therefore, in this case, the laser processing device equipped with the laser oscillator becomes larger and more expensive. Furthermore, in this case, there is a risk that components (e.g., a condenser lens) included in the optical system that irradiates the laser beam toward the ingot may be damaged, deteriorating its optical characteristics.

[0010] In view of this, an object of the present invention is to provide a method for manufacturing a substrate that can improve throughput when manufacturing a substrate from a structure such as an ingot using a laser beam without increasing the output of the laser beam. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a method for manufacturing a substrate from a structure made of a single-crystal material, the method comprising: a separation layer forming step of irradiating a surface side of the structure with a laser beam having a wavelength that transmits the single-crystal material to form a separation layer within the structure, the separation layer including a modified portion and cracks extending from the modified portion; and a separation step of separating the substrate from the structure starting from the separation layer, wherein the separation layer is formed by branching the laser beam to form multiple focal points aligned along a first direction parallel to a specific crystal plane of the single-crystal material, and then relatively moving the structure and the multiple focal points along a second direction parallel to the surface and the specific crystal plane. In this substrate manufacturing method, the structure may be an ingot. Furthermore, in this substrate manufacturing method, the first direction may be non-parallel to the surface. According to another aspect of the present invention, there is provided a processing method for forming a delamination layer including a modified portion and cracks extending from the modified portion within a structure made of a single crystal material, the processing method comprising: forming the delamination layer within the structure by irradiating the surface side of the structure with a laser beam having a wavelength that transmits through the single crystal material, wherein the delamination layer is formed within the structure by relatively moving the structure and the multiple focal points along a second direction parallel to each of the surface and the specific crystal plane, while branching the laser beam to form multiple focal points aligned along a first direction parallel to a specific crystal plane of the single crystal material. Note that in this processing method, the structure is an ingot, and the first direction may be non-parallel to the surface. [Effects of the Invention]

[0012] In the present invention, a peeling layer is formed by branching a laser beam to form multiple focal points aligned along a first direction parallel to a specific crystal plane of the single crystal material that constitutes a structure such as an ingot, and then moving the structure and the multiple focal points relatively along a second direction parallel to this specific crystal plane.

[0013] In this case, modified regions are formed around each of the multiple light-focusing points, and cracks tend to propagate from the modified regions along the specific crystal planes. Cracks that propagate along the specific crystal planes tend to be longer than cracks that propagate randomly.

[0014] Therefore, in this case, it is possible to lengthen the crack formed inside the structure such as an ingot without increasing the output of the laser beam, and as a result, in the present invention, it is possible to improve the throughput when manufacturing substrates from the structure such as an ingot. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view schematically showing an example of an ingot used in manufacturing a substrate. [Figure 2] FIG. 2 is a top view schematically showing the ingot shown in FIG. [Figure 3] FIG. 3 is a side view schematically showing the ingot shown in FIG. [Figure 4] FIG. 4 is a flow chart schematically showing an example of a method for manufacturing a substrate from an ingot. [Figure 5] FIG. 5 is a diagram schematically illustrating an example of a laser processing device for performing the release layer forming step (S1) shown in FIG. [Figure 6] FIG. 6 is a top view schematically showing how an ingot is held by a holding table of the laser processing device. [Figure 7] FIG. 7 is a flow chart schematically illustrating an example of the release layer forming step (S1) shown in FIG. [Figure 8] FIG. 8 is a top view schematically showing the laser beam irradiation step (S11) shown in FIG. [Figure 9] FIG. 9 is a cross-sectional view schematically showing an ingot to be irradiated with a laser beam in the laser beam irradiation step (S11) shown in FIG. [Figure 10] 10(A) and 10(B) are each a partial cross-sectional side view schematically showing an example of the separation step (S2) shown in FIG. [Figure 11] 11(A) and 11(B) are each a partial cross-sectional side view schematically showing another example of the separation step (S2) shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view schematically showing an example of an ingot used in manufacturing a substrate. Fig. 2 is a top view schematically showing the ingot shown in Fig. 1, and Fig. 3 is a side view schematically showing the ingot shown in Fig. 1.

[0017] 1 to 3 is made of a hexagonal single crystal material. In addition, in Fig. 1 and Fig. 3, the crystal planes of this single crystal material are also shown, and in Fig. 2 and Fig. 3, the crystal orientation of this single crystal material is also shown.

[0018] The ingot 11 is, for example, a cylindrical LT ingot having a front surface 11a and a back surface 11b that are parallel to each other. An orientation flat 13 is formed on a side surface 11c of the ingot 11.

[0019] The center C of the ingot 11 is located in the crystal orientation [-12-10] when viewed from the orientation flat 13. That is, in the orientation flat 13, the crystal plane (-12-10) is exposed.

[0020] The c-axis (crystal orientation

[0001] ) of the single crystal material constituting the ingot 11 is inclined with respect to the perpendicular line 11d of the front surface 11a and the back surface 11b. For example, the angle (off angle) θ off is approximately 48°.

[0021] Here, the angle between the crystal plane (10-12), which is a crystal plane parallel to the crystal orientation [-12-10], and the c-plane (crystal plane (0001)) is approximately 57°. Therefore, the angle α between this crystal plane (10-12) and the front surface 11a or back surface 11b of the ingot 11 is approximately 9°.

[0022] 4 is a flowchart schematically illustrating an example of a method for manufacturing a substrate from an ingot 11. In this method, first, a peeling layer including a modified portion and cracks extending from the modified portion is formed inside the ingot 11 (peeling layer forming step: S1).

[0023] Fig. 5 is a diagram schematically illustrating an example of a laser processing apparatus for performing the release layer forming step (S1). Note that the X-axis direction and the Y-axis direction shown in Fig. 5 are directions perpendicular to each other on a horizontal plane, and the Z-axis direction is a direction (vertical direction) perpendicular to both the X-axis direction and the Y-axis direction.

[0024] 5 has a disk-shaped holding table 4. This holding table 4 has, for example, a circular upper surface (holding surface) parallel to the X-axis direction and the Y-axis direction. The holding table 4 also has a disk-shaped porous plate (not shown) whose upper surface is exposed on this holding surface.

[0025] Furthermore, this porous plate is connected to a suction source (not shown) such as an ejector via a flow path formed inside the holding table 4. When this suction source is activated, a suction force acts on the space near the holding surface of the holding table 4. This allows, for example, the holding table 4 to hold an ingot 11 placed on the holding surface.

[0026] A laser beam irradiation unit 6 is provided above the holding table 4. The laser beam irradiation unit 6 has a laser oscillator 8. The laser oscillator 8 has, for example, Nd:YAG or the like as a laser medium.

[0027] The laser oscillator 8 irradiates the ingot 11 with a laser beam LB having a wavelength (for example, 1064 nm) that is transmitted through the single crystal material (LT). The laser beam LB is pulsed, with a frequency of, for example, 20 kHz to 80 kHz, typically 50 kHz, and a pulse duration of, for example, 5 ps to 30 ps, ​​typically 15 ps.

[0028] This laser beam LB is adjusted by an attenuator 10 so that its average output (power) is, for example, 0.5 W to 2.0 W, typically 1.3 W, and is then supplied to a branching unit 12. This branching unit 12 has, for example, a spatial light modulator including a liquid crystal phase control element called LCoS (Liquid Crystal on Silicon) and / or a diffractive optical element (DOE).

[0029] The branching unit 12 branches the laser beam LB so that the laser beam LB irradiated from the irradiation head 16 described later onto the holding surface side of the holding table 4 forms multiple (for example, 4 to 20, typically 10) focal points arranged along a predetermined direction perpendicular to the X-axis direction.

[0030] Specifically, the branching unit 12 branches the laser beam LB so that the distance I in the Y-axis direction between a pair of adjacent focusing points among the multiple focusing points is, for example, 5 μm to 30 μm, typically 12.5 μm, and the angle β formed by the predetermined direction and a plane parallel to the X-axis direction and the Y-axis direction (XY plane) is equal to the angle α shown in FIG. 3.

[0031] The laser beam LB branched by the branching unit 12 is reflected by a mirror 14 and guided to an irradiation head 16. The irradiation head 16 contains a condenser lens (not shown) that condenses the laser beam LB and the like.

[0032] The numerical aperture (NA) of this condenser lens is, for example, 0.75. The laser beam LB condensed by this condenser lens is irradiated onto the holding surface side of the holding table 4, or more simply, directly below, with the central region of the lower surface of the irradiation head 16 as the emission region.

[0033] Furthermore, the irradiation head 16 of the laser beam irradiation unit 6 and an optical system (e.g., mirror 14, etc.) for guiding the laser beam LB to the irradiation head 16 are connected to a movement mechanism (not shown). This movement mechanism includes, for example, a ball screw and a motor. When this movement mechanism operates, the emission area of ​​the laser beam LB moves along the X-axis direction, the Y-axis direction, and / or the Z-axis direction.

[0034] Furthermore, in the laser processing device 2, by operating this movement mechanism, it is possible to adjust the positions (coordinates) in the X-axis direction, Y-axis direction, and Z-axis direction of the multiple focusing points at which the laser beam LB irradiated from the irradiation head 16 onto the holding surface side of the holding table 4 is focused.

[0035] When the ingot 11 is carried into the laser processing apparatus 2, the ingot 11 is held by the holding table 4 with the surface 11a facing upward. Figure 6 is a top view schematically showing the state in which the ingot 11 is held by the holding table 4 of the laser processing apparatus 2.

[0036] Specifically, first, the ingot 11 is placed on the holding table 20 so that the direction from the orientation flat 13 toward the center C of the ingot 11 (crystal orientation [-12-10]) coincides with the X-axis direction and this center C overlaps with the center of the holding surface of the holding table 20.

[0037] Next, a suction source is operated that communicates with the porous plate exposed on the holding surface of the holding table 4. This causes the ingot 11 to be held by the holding table 4 with the front surface 11a and back surface 11b of the ingot 11 parallel to the XY plane.

[0038] Then, the separation layer forming step (S1) is carried out once the ingot 11 is held by the holding table 4. Fig. 7 is a flow chart schematically showing an example of the separation layer forming step (S1).

[0039] In this peeling layer forming step (S1), first, irradiation head 16 is moved so that an area located at one end of ingot 11 in the Y-axis direction is positioned in the X-axis direction from irradiation head 16 in a plan view.

[0040] Next, when irradiating the ingot 11 with the laser beam LB, the irradiation head 16 is raised and lowered so that the multiple focal points are positioned inside the ingot 11. For example, the irradiation head 16 is raised and lowered so that the average depth of the multiple focal points from the surface 11a of the ingot 11 is, for example, 120 μm to 200 μm, typically 160 μm.

[0041] Next, with multiple focal points where the laser beam LB is focused positioned inside the ingot 11, the ingot 11 and the multiple focal points are moved relatively along the X-axis direction (crystal orientation [-12-10]) (laser beam irradiation step: S11).

[0042] FIG. 8 is a top view that schematically shows the laser beam irradiation step (S11), and FIG. 9 is a cross-sectional view that schematically shows the ingot 11 that is irradiated with the laser beam LB in the laser beam irradiation step (S11).

[0043] Specifically, in this laser beam irradiation step (S11), while irradiating the laser beam LB from the irradiation head 16 toward the holding table 4, the irradiation head 16 is moved so as to pass from one end to the other end of the ingot 11 in the X-axis direction (crystal orientation [-12-10]) in a planar view (see Figure 8).

[0044] As a result, modified regions 15a with a disordered crystal structure are formed around each of the plurality of light-focusing points inside the ingot 11 (see FIG. 9). Furthermore, when the modified regions 15a are formed inside the ingot 11, the volume of the ingot 11 expands, causing internal stress in the ingot 11.

[0045] Then, cracks 15b propagate from the modified portions 15a inside the ingot 11 so as to relieve this internal stress. As a result, a peeling layer 15 including a plurality of modified portions 15a and cracks 15b propagating from each of the plurality of modified portions 15a is formed inside the ingot 11.

[0046] Here, the front surface 11a and the back surface 11b of the ingot 11 are each parallel to the XY plane, and the angle β formed by the above-mentioned predetermined direction (the direction in which the multiple focal points where the laser beam LB is focused are aligned) and the XY plane is equal to the angle α shown in Figure 3. Therefore, the multiple focal points are aligned along the crystal plane (10-12) of the single crystal material that constitutes the ingot 11.

[0047] In this case, the multiple modified areas 15a formed by irradiation with the laser beam LB are also aligned along the crystal plane (10-12) of the single crystal material, and the cracks 15b extending from each of the multiple modified areas 15a also tend to become long along the crystal plane (10-12).

[0048] Then, in a situation where irradiation of the laser beam LB onto the entire area of ​​the ingot 11 (all areas from the area located at one end in the Y-axis direction to the area located at the other end) has not been completed (step (S12): NO), the position where multiple focal points are formed and the ingot 11 are moved relatively along the Y-axis direction (indexing and feeding step: S13).

[0049] In this indexing step (S13), for example, the irradiation head 16 is moved along the Y-axis direction by 300 μm to 800 μm, typically 500 μm, so that the irradiation head 16 approaches the other end of the ingot 11.

[0050] Next, the above-described laser beam irradiation step (S11) is performed again. That is, while irradiating the holding table 4 with the laser beam LB from the irradiation head 16, the irradiation head 16 is moved so as to pass from one end to the other end of the ingot 11 in the X-axis direction (crystal orientation [-12-10]) in plan view.

[0051] Furthermore, the indexing step (S13) and the laser beam irradiation step (S11) are alternately repeated until the peeling layer 15 is formed over the entire area of ​​the ingot 11. Then, when the irradiation of the laser beam LB over the entire area of ​​the ingot 11 is completed (step (S12): YES), the peeling layer formation step (S1) shown in FIG.

[0052] In the peeling layer forming step (S1) of the present invention, the above-described irradiation of the laser beam LB over the entire area of ​​the ingot 11 may be repeated multiple times (for example, four times). In this case, the density of the modified regions 15a and cracks 15b formed inside the ingot 11 can be increased, and / or the cracks 15b can be made even longer.

[0053] Then, when the separation layer forming step (S1) is completed, the substrate is separated from the ingot 11 starting from the separation layer 15 (separation step: S2). Figures 10(A) and 10(B) are partial cross-sectional side views each showing a schematic example of the separation step (S2) shown in Figure 4.

[0054] This separation step (S2) is performed, for example, in a separation apparatus 18 shown in Figures 10(A) and 10(B). This separation apparatus 18 has a holding table 20 that holds the ingot 11 on which the peeling layer 15 has been formed. This holding table 20 has a circular upper surface (holding surface), and a porous plate (not shown) is exposed on this holding surface.

[0055] Furthermore, this porous plate is connected to a suction source (not shown) such as an ejector via a flow path or the like provided inside the holding table 20. When this suction source is activated, a suction force acts on the space near the holding surface of the holding table 20. This allows, for example, the ingot 11 placed on the holding surface to be held by the holding table 20.

[0056] A separation unit 22 is provided above the holding table 20. The separation unit 22 has a cylindrical support member 24. A ball screw type lifting mechanism (not shown) and a rotation drive source such as a motor are connected to the upper part of the support member 24.

[0057] Operating this lifting mechanism raises and lowers the support member 24. Operating this rotation drive source also rotates the support member 24 around a rotation axis that passes through the center of the support member 24 and is perpendicular to the holding surface of the holding table 20.

[0058] The lower end of the support member 24 is fixed to the center of the upper part of a disk-shaped base 26. A plurality of movable members 28 are provided below the outer peripheral region of the base 26 at approximately equal intervals along the circumferential direction of the base 26. Each movable member 28 has a plate-shaped erected portion 28a extending downward from the lower surface of the base 26.

[0059] The upper end of this standing portion 28a is connected to an actuator such as an air cylinder built into the base 26, and by operating this actuator, the movable member 28 moves along the radial direction of the base 26. In addition, on the inner surface of the lower end of this standing portion 28a, a plate-shaped wedge portion 28b is provided which extends toward the center of the base 26 and becomes thinner as it approaches the tip.

[0060] When the ingot 11 is carried into the separation device 18, the ingot 11 is held by the holding table 20 with the front surface 11a facing upward. Specifically, first, the ingot 11 is placed on the holding table 20 so that the center of the back surface 11b of the ingot 11 and the center of the holding surface of the holding table 20 are aligned.

[0061] Next, a suction source communicating with the porous plate exposed on the holding surface is operated, whereby the ingot 11 is held by the holding table 20. Then, once the ingot 11 is held by the holding table 20, the separation step (S2) is carried out.

[0062] Specifically, first, the actuator is operated to position each of the plurality of movable members 28 radially outward from the base 26. Next, the lifting mechanism is operated to position the tip of the wedge portion 28b of each of the plurality of movable members 28 at a height corresponding to the peeling layer 15 formed inside the ingot 11.

[0063] Next, the actuator is operated so that the wedge portion 28b is driven into the side surface 11c of the ingot 11 (see FIG. 10(A)). Next, the rotation drive source is operated so that the wedge portion 28b driven into the side surface 11c of the ingot 11 rotates. Next, the lifting mechanism is operated so as to lift the wedge portion 28b (see FIG. 10(B)).

[0064] As described above, after wedge portion 28b is driven into side surface 11c of ingot 11 and rotated, wedge portion 28b is raised, whereby cracks 15b included in each separation layer 15 are further extended so as to connect adjacent separation layers 15. As a result, the front surface 11a side and the back surface 11b side of ingot 11 are separated. That is, substrate 17 is produced from ingot 11, starting from separation layer 15.

[0065] It should be noted that the wedge portion 28b does not need to be rotated if the front surface 11a and the back surface 11b of the ingot 11 are separated when the wedge portion 28b is driven into the side surface 11c of the ingot 11. Alternatively, the actuator and the rotary drive source may be operated simultaneously to drive the rotating wedge portion 28b into the side surface 11c of the ingot 11.

[0066] In the method shown in Figure 4, the laser beam LB is branched so as to form multiple focal points aligned along a direction (first direction) parallel to the crystal plane (10-12) of the single crystal material constituting the ingot 11, and the ingot 11 and the multiple focal points are moved relatively along a direction parallel to this crystal plane (10-12), specifically, along the crystal orientation [-12-10] (second direction), thereby forming a peeling layer 15.

[0067] In this case, modified regions 15a are formed around each of the plurality of light-converging points, and cracks 15b tend to extend from the modified regions 15a along the crystal plane (10-12). The cracks 15b extending along the crystal plane (10-12) tend to be longer than cracks extending randomly.

[0068] Therefore, in this case, it is possible to lengthen crack 15b formed inside ingot 11 without increasing the output of laser beam LB. As a result, in the method shown in Fig. 4, it is possible to improve the throughput when manufacturing substrate 17 from ingot 11.

[0069] The above-described method for manufacturing a substrate is one embodiment of the present invention, and the present invention is not limited to the above-described method. For example, the ingot used to manufacture a substrate in the present invention is not limited to the ingot 11 shown in Figures 1 to 3.

[0070] Specifically, in the present invention, a substrate may be manufactured from an ingot having a notch formed on the side surface. Alternatively, in the present invention, a substrate may be manufactured from an ingot having neither an orientation flat nor a notch formed on the side surface. Furthermore, in the present invention, a substrate may be manufactured from a cylindrical ingot made of a single crystal material other than LT.

[0071] Furthermore, the structure of the laser processing device used in the release layer forming step (S1) of the present invention is not limited to the structure of the above-described laser processing device 2. For example, the release layer forming step (S1) may be performed using a laser processing device provided with a movement mechanism that moves the holding table 4 along each of the X-axis direction, the Y-axis direction, and / or the Z-axis direction.

[0072] Alternatively, the peeling layer forming step (S1) of the present invention may be performed using a laser processing apparatus in which a scanning optical system capable of changing the direction of the laser beam LB emitted from the irradiation head 16 is provided in the laser beam irradiation unit 6. The scanning optical system includes, for example, a galvanometer scanner, an acousto-optical device (AOD), and / or a polygon mirror.

[0073] That is, in the peeling layer formation step (S1) of the present invention, it is sufficient that the ingot 11 held by the holding table 4 and the multiple focal points at which the laser beam LB irradiated from the irradiation head 16 is focused can move relatively along each of the X-axis direction, Y-axis direction, and Z-axis direction, and there is no limitation on the structure for this purpose.

[0074] Furthermore, the direction in which the multiple focal points are arranged (first direction) in the peeling layer formation step (S1) of the present invention is not limited to a direction parallel to the crystal plane (10-12). That is, in the present invention, it is sufficient that the first direction is set to be parallel to a specific crystal plane of the single crystal material, and the specific crystal plane can be selected arbitrarily.

[0075] Furthermore, in the present invention, it is not an essential feature to form the peeling layer 15 throughout the entire interior area of ​​the ingot 11 in the peeling layer forming step (S1). For example, if the crack 15b extends to the area near the side surface 11c of the ingot 11 in the separation step (S2), the peeling layer 15 may not be formed in part or all of the area near the side surface 11c of the ingot 11 in the peeling layer forming step (S1).

[0076] Furthermore, the separation step (S2) of the present invention may be performed using an apparatus other than the separation apparatus 18 shown in Figures 10(A) and 10(B). For example, in the separation step (S2) of the present invention, the substrate 17 may be separated from the ingot 11 by suctioning the surface 11a side of the ingot 11.

[0077] 11(A) and 11(B) are partial cross-sectional side views each showing an example of the separation step (S2) performed in this manner. The separation apparatus 30 shown in FIG. 11(A) and FIG. 11(B) has a holding table 32 for holding the ingot 11 on which the peeled layer 15 is formed.

[0078] The holding table 32 has a circular upper surface (holding surface), and a porous plate (not shown) is exposed on this holding surface. Furthermore, this porous plate is in communication with a suction source (not shown), such as a vacuum pump, via a flow path or the like provided inside the holding table 32. Therefore, when the suction source is operated, a suction force acts on the space near the holding surface of the holding table 32.

[0079] A separation unit 34 is provided above the holding table 32. The separation unit 34 has a cylindrical support member 36. A ball screw type lifting mechanism (not shown), for example, is connected to the top of the support member 36, and the separation unit 34 moves up and down by operating this lifting mechanism.

[0080] The lower end of the support member 36 is fixed to the center of the upper part of a disk-shaped suction plate 38. A plurality of suction ports are formed in the lower surface of the suction plate 38, and each of the plurality of suction ports is connected to a suction source (not shown), such as a vacuum pump, via a flow path or the like provided inside the suction plate 38. Therefore, when the suction source is operated, a suction force acts on the space near the lower surface of the suction plate 38.

[0081] In the separation device 30, the separation step (S2) is performed, for example, in the following order: Specifically, first, the ingot 11 is placed on the holding table 32 so that the center of the back surface 11b of the ingot 11 on which the peeling layer 15 is formed is aligned with the center of the holding surface of the holding table 32.

[0082] Next, a suction source communicating with the porous plate exposed on the holding surface is operated so that the ingot 11 is held by the holding table 32. Next, the lifting mechanism is operated to lower the separation unit 34 so that the lower surface of the suction plate 38 contacts the surface 11a of the ingot 11.

[0083] Next, a suction source communicating with the plurality of suction ports is operated so that the front surface 11a side of the ingot 11 is sucked through the plurality of suction ports formed in the suction plate 38 (see FIG. 11(A)). Next, the lifting mechanism is operated to lift the separation unit 34 so that the suction plate 38 is separated from the holding table 32 (see FIG. 11(B)).

[0084] At this time, an upward force acts on the front surface 11a side of the ingot 11, which is sucked through the multiple suction ports formed in the suction plate 38. As a result, the cracks 15b contained in each separation layer 15 extend further so as to connect adjacent separation layers 15, separating the front surface 11a side and the back surface 11b side of the ingot 11. In other words, a substrate 17 is produced from the ingot 11, starting from the separation layer 15.

[0085] Furthermore, in the separation step (S2) of the present invention, prior to separation of the front surface 11a side and the back surface 11b side of the ingot 11, ultrasonic waves may be applied to the front surface 11a side of the ingot 11. In this case, the cracks 15b contained in each peeling layer 15 further extend so as to connect adjacent peeling layers 15, making it easier to separate the front surface 11a side and the back surface 11b side of the ingot 11.

[0086] Furthermore, in the present invention, prior to the separation layer forming step (S1), the surface 11a of the ingot 11 may be flattened by grinding or polishing (flattening step). For example, this flattening may be performed when manufacturing a plurality of substrates from the ingot 11.

[0087] Specifically, when the ingot 11 is separated at the separation layer 15 to produce the substrate 17, the newly exposed surface of the ingot 11 has irregularities that reflect the distribution of the modified portions 15a and cracks 15b contained in the separation layer 15. Therefore, when a new substrate is produced from this ingot 11, it is preferable to flatten the surface of the ingot 11 prior to the separation layer formation step (S1).

[0088] This makes it possible to suppress diffuse reflection of the laser beam LB irradiated onto the ingot 11 in the peeling layer forming step (S1) on the surface of the ingot 11. Similarly, in the present invention, the surface of the substrate 17 separated from the ingot 11 on the peeling layer 15 side may be flattened by grinding or polishing.

[0089] In addition, the structures and methods according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0090] 2: Laser processing equipment 4: Holding table 6: Laser beam irradiation unit 8: Laser oscillator 10: Attenuator 11: Ingot (11a: surface, 11b: back, 11c: side, 11d: perpendicular) 12: Branch unit 13: Orientation Flat 14: Mirror 15: Peeling layer (15a: modified part, 15b: crack) 16: Irradiation head 17: Circuit board 18: Separation device 20: Holding table 22: Separation unit 24: Support member 26: Foundation 28: Movable member (28a: Standing portion, 28b: Wedge portion) 30: Separation device 32: Holding table 34: Separation unit 36: Support member 38: Suction plate

Claims

1. A method for manufacturing a substrate from a structure made of a single crystal material, comprising: a peeling layer forming step of forming a peeling layer including a modified portion and cracks extending from the modified portion inside the structure by irradiating a laser beam having a wavelength that is transmitted through the single crystal material from the surface side; a separation step of separating the substrate from the structure starting from the release layer; A method for manufacturing a substrate, in which, in the peeling layer formation step, the laser beam is branched to form multiple focal points aligned along a first direction parallel to a specific crystal plane of the single crystal material, and the structure and the multiple focal points are moved relatively along a second direction parallel to each of the surface and the specific crystal plane, thereby forming the peeling layer.

2. The method of claim 1 , wherein the structure is an ingot.

3. The method for manufacturing a substrate according to claim 1 , wherein the first direction is non-parallel to the surface.

4. A processing method for forming a peeling layer including a modified portion and a crack extending from the modified portion inside a structure made of a single crystal material, the method comprising: a peeling layer forming step of forming the peeling layer inside the structure by irradiating a laser beam having a wavelength that is transmitted through the single crystal material from a surface side; In the peeling layer formation step, the laser beam is branched to form a plurality of focal points aligned along a first direction parallel to a specific crystal plane of the single crystal material, and the structure and the plurality of focal points are moved relatively along a second direction parallel to each of the surface and the specific crystal plane, thereby forming the peeling layer.

5. the structure is an ingot; The method of claim 4 , wherein the first direction is non-parallel to the surface.

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